Molecular genetics Flashcards
What steps of the cell cycle constitute interphase
All except mitosis i.e. G0, G1, S & G2
In interphase the genetic material and organelles of the cell duplicate
The chromatids (half of chromosome that we get from each parent) duplicate and are joined together at nucleus:
- 46 chromosomes become 92 chromatids
Outline the stages of mitosis
Prophase:
- Chromatids condense
- Spindle fibres form
Metaphase:
- Nucleus breaks down
- Spindle fibres attach to each chromatid and they line up at equator of cell (metaphase plate)
Anaphase:
- The chromosomes separate into chromatids through the shortening of spindle fibres dividing the centromeres
- Aligned at opposites of the cells
Telophase:
- New nuclear membrane forms around each set of chromosomes
- Spindle fibres split down
- Cytokinesis - the cell membrane splits via pinching into two separate cells separating each set of chromatids
Outline the stages of mitosis
Prophase:
Metaphase
Anaphase
Telophase
How does meisosis differ to mitosis?
In mitosis cells divide to form two daughter cells each with same amount of chromosomes as the parent (46)
In meiosis cells divide to form 4 daughter cells with half the amount of chromosomes as the parent (23):
- The process involves the same prophase, metaphase, telophase and cytokinesis however this happens twice
- The first time round in interphase rather than chromatids duplicating and attaching at centromeres whole new chromosomes are produced
- Therefore in the first metaphase M1 these line up side by side –> when anaphase splits them and telophase forms a ring around the new cells each has the same amount of DNA as at the start
- A seconds P2,M2, T2 and cytokinesis then occurs dividing the genetic material by half
What is crossing over?
Occurs in prophase 1 of meisosis - ends of sister chromosomes may overlap at similar genes positions sharing DNA to form recombinant chromosomes
What do the numbers 1, 2, 3 , 4 represent
1 - telomere
2 - centromere
3 - p i.e. short arm of chromosome
4 - q i.e. long arm of chromosome
What is a metacentric vs acrocentric/submetacentric chromosome?
Metacentric chromosome - centromere is at the centre (i.e p and q arms are equal length)
Acrocentric/submetacentric - centromere is at one end
Other types of chromosome (telocentric and holocentric) are not seen in humans
What name is given to cells with the incorrect number of chromosomes?
Aneuploid cells
- Aneuploidy can occur from extra number or one chromosome (trisomy 21 for example) or rarely if total chromosome number multiples (triploidy or tetraploidy) however the later to cause spontaneous abortion
How does trisomy/monosomies arises?
From non-disjunction during meisosis - a failure of the chromatids/chromosomes to separate
This can lead to one gamete having double the sets of one chromosome than it should - produces trisomy OR the gamete may have no set of one chromosome - produces monosomy
Moasiacism occurs when the non-disjunction occurs in mitosis after the gametes fuse - this causes the production of two cell lineages (with and without trisomy) leading to milder symptoms
Only trisomy 21 survives into adulthood, trisomies 13 and 18 often die in childhood
What are the genetic abnormalities of
a) Downs syndrome
b) Turners syndrome
c) Pataus syndrome
d) Edwards syndrome
e) Metafemale
a) Trisomy 21
b) Turner’s syndrome - single X chromosome 45X
c) Trisomy 13
d) Trisomy 18
e) Trisomy X chromosome
What are the gestational signs of down’s?
Reduced alpha feto protein
Increased bHCG
A single nuchal fold on USS
Outline some clinical signs of downsyndrome?
Prominent epicanthal folds
Single palmar crease
Low set ears
Intellectual disability
Hypothyroidism
Heart abnormalities (ASD)
How does Edward’s syndrome present?
More common in girls > boys
Rocker bottom feet
Low set ears
Severe intellectual disability
Small jaw (microganthia)
Congenital heart disease
Clenched hands
Prominent occiput
Widely spaced eyes
Overlapping fingers
How does Patau’s syndrome present?
Microcephaly
Microphthalmia
Cleft lip/palate
Polydactyly
Colomba eye
Intellectual disability
Abnormal forebrain structure
How does Turner’s syndrome present?
Short stature
Webbed neck
Low hairline
Retrognathism (posterior position of mandible)
Disharmonic IQ profile - normal verbal, reduced performance.
Usually only X is maternal in origin (80%) if paternal then better IQ.
This differs to other syndromes described where often aneuploidy arises in the maternal gamete
What is a nucleoside?
A molecule made of a nitrogenous base and a pentose sugar - when phosphorylated they are nucleotides - the components of nucleic acid
What is DNA made of?
Deoxyribose-phosphate backbone and bases of nucleic acid - two stands joined together by hydrogen bonds
Bases can be purines (Adenosine or Guanine) or pyrimidine (Thymine or Cystosine)
How many base pairs make a codon?
3 - each codon indicates a specific amino acid. There are 20 amino acids. 10 are essential and are not derived from food but need to be synthesised within the body
What are protein coding regions
Name two type of introns sequences
Interspersed:
- Long interspersed
- Short interspersed
TANDEM REPEATs:
Satelite:
- Large series of repeats
Microsatelite - telomeric repeats (chromosomal integrity)
- hypervariable repeats (DNA finger-printing)
Minisatelite - single, di or trinucleotide repeats
What does hnRNA refer to?
What does hnRNA refer to?
Heterogenous nuclear RNA - RNA that contains non codon regions (introns)
Splicing is the process that removes these regions resulting in messenger RNA that leaves the nucleus
What do nucleosomes do?
Nucleosomes remove non-coding RNA from hnRNA to produce mRNA
Where are ribosomes found?
In the cytoplasm attached to rough endoplasmic reticulum
Name the 3 stages of translation
Initiation - methionine containing tRNA binds to the polpeptide P site of the Ribosome
Elongation - at the aminoacyl A site each new tRNA binds (with attached amino acids bind). Amino acids are bound 1 by 1
Termination - termination sequence UAG, UAA or UGA signals end of protein
Modification is extra post translation changes that occur to the protein before it becomes functionally active. This occurs in the ER or golgi bodies - it can occur spontaneously as translation occurs
What is aminoacyl-tRNA synthetase?
The enzyme that binds tRNA to specific amino acids in the presence of Mg2+
What is translocation
A reciprocal exchange of genetic material between 2 chromosomes
In Robertsonian translocation exchange is not reciprocal and from 2 chromosomes the p arms are lost and one metacentric chromosome is formed.
i.e from one 14 and one 21 - produces 14/21 (alongside remaining 14 and remaining 21)
- When meisosis gametes formed can contain 14/21 and 21 –> produce trisomy 21 during fertilisation
- OR gamete may only have one 14 or 21 –> monosomy 14 or monosomy 21
Robertsonian translocation accounts for 4% of downs
Robertsonian translocation chromosome can be inherited from either parent
Outline the genetic abnormalities and brief symptoms associated with
a) DiGeorge (Velocardiofacial)
b) William Syndrome
c) Smith Magnesis Syndrome
d) Angelmann Syndrome
e) Prader Willi
f) Cru-di-Chat
a) 22q.11.2 autosomal dominant - 25% get psychosis, mild to moderate LD, facial deformity including cleft palate, absent or malformed parathyroid (hypocalcaemia), articulatory problems, broad nasal bridge
b) 7.11 microdeletion - hypercalcium, supravalvular aortic stenosis, speech superficially fluent, mild-moderate LD, disinhibited, hyperacusis
c) 17.11.2 microdeletion - mild-moderate self-harm, pulling off nails, sleep disturbances and hugging, inserting of foreign objects, moderate to severe LD
d) 15q11-13 maternal deletion - developmental delay, low IQ, jerking movements and hand flapping
e) 15q11-13 deletion - obesity, small stature, decreased IQ, skin picking, hyperphagia - small gonads
f) 5p chromosome deletion (locus 5p.15.2) - small facial features (poorly developed), cat-like cry, feeding difficulties
Name the 3 mendelian laws
Law of uniformity - the offspring must inherent either trait from each parent
Principle of segregation - only one allele from each parent passes to the child and is from pure chance - the parental alleles separates during meiosis. Thus if A and B alleles with Mother AB and Father AB child can be AA, BB or AB
Independent assortment - different traits do not depend on each other
Outline how the risk of Schizophrenia varies in the following
a) General population
b) First cousin
c) Aunt/Uncle
d) Niece/nephew
e) Grandchildren
f) Parent
g) Half sibling
h) Full sibling
i) Children
j) Fraternal twins (non-identical)
k) Off spring of parents with Schz
l) Identical twins
a) General population 1%
b) First cousin 2%
c) Aunt/Uncle 2%
d) Niece/nephew 4%
e) Grandchildren 5%
f) Parent 6%
g) Half sibling 6%
h) Full sibling 9%
i) Children 13%
j) Fraternal twins (non-identical) 17%
k) Off spring of parents with Schz 46%
l) Identical twins 48%
If there is a mutation affecting the transcriptional activity of a new gene it is likely to affect?
The promoter region of the gene - the area of DNA that RNA polymerase binds to in order to begin mRNA synthesis from DNA
What are the 5 conditions that need to be met to ensure Hardy-Weinberg Equilibrium
a) No mutations
b) No loss or gain of genetic info
c) Random mating
d) Population is large enough to ensure no genetic drift - i.e. random chance of geneotype or allelic frequency changing
e) No natural selection - i.e. a genotype or allele cannot confer a survival advantage
What is the Hardy-Weinberg Equation
p2 + 2pq + q2 = 1
p2 (autosomal dominant)
2pq (heterozygous)
q2 (autosomal recessive)
What type of analysis determines the method of inheritance using family data?
Segregation analysis
What is linkage analysis
A method that identifies a piece of DNA of known location that is present in affected individuals (inherited) but not unaffected individuals
- from here the disease gene must be close
Lyonisation is the process where…
One of the X chromosomes is made inactivated to prevent a toxic double dose of x-linked genes.
The x-chromosome made inactive is called a Barr body
This condition results in multiple non-malignant tumours growing in the brain and body of an individual?
Tuberous sclerosis - implicated genes are TSC1 and TSC2
Psychiatric co-morbidities include Autism, ADHD, Anxiety and Psychosis
Seizures, developmental delay and skin lesions
It is autosomal dominant with variable expression but 95% penetrance
Name some diseases with mitochondrial inheritance
Leber’s hereditary optic neuropathy
Kearn’s Sayre syndrome
Name an anagram to remember DiGeorge Syndrome
Cardiac abnormalites
Abnormal faces
Thymic aplasia - recurrent infections
Cleft palate
Hypocalcaemia/Hypercalcaemia
2
2
What are the trinucleotide repeats seen in
a) Huntington’s
b) Fragile X syndrome
c) Muscular dystrophy
d) Friedrich’s ataxia
a) CAG
b) CGG
c) CTT
d) gAA
What are the symptoms of fragile X syndrome and what gene is affected?
Affects FMR1 gene - CGG repeats at exon sites (FRAXA, FRAXE, FRAXF)
If > 52 repeats - destablisation during spermatogenesis or oocytogenesis and expansion occurs
Clinical symptoms if > 200 repeats:
- Men - large testes, lower IQ, prominent ear lobes, high pitch voice and mental retardation
- Women -> mild LD, early menopause
If 55-200 then premutation:
- Men –> intention tremor and ataxia later in life
- Women –> premature ovarian failure and cognitive/behavioural difficulties
- Shows anticipation
What chromosome is Huntington’s expressed on?
Chromosome 4 - 4p16.3 - a trinucleotide repeat of CAG here (40-55)
Unlike x-linked diseases here if paternal mutation inherited - there is greater repeats and anticipation (in x-linked diseases tends to be if maternal gene then greater anticipation)
What mechanism is responsible for genomic imprinting?
DNA methylation
Parent of origin phenomenon - i.e. where it matters if gene inherited from mother or dad which syndrome occurs
Prader Willi 15q11-13 - paternally inherited (20% of cases come from maternal uniparental disomy - i.e. both copies from mum)
Angelman Syndrome 15q11-13 matrernally inherited (only 4% of cases are from paternal uniparental disomy)
Outline how the following disorders are inherited and briefly their symptoms:
a) Tuberous Sclerosis
b) Treacher Collins Syndrome
c) Apert syndrome
d) Noonan syndrome
e) Hurler syndrome
f) Lesch-Nyan syndrome
a) Auto Dominant but most spontaneous 9q34/16p13 - Ash leaf macules, brain hamartomas, mental retardation, adenoma sebaceum, heart and kidney cysts
b) Auto dominant 5q31 - down slanting eyebrows, maxo/mandibular hypoplasia, malformed pinna, moderate LD
c) Auto dominant 10q - craniosynostosis (fusing of skull), mitten hands, trapezoid mouth, variable LD
d) Autosomal dominant - Chr 12 - LD, cryptorchidism, pulmonary stenosis, webbed neck, short stature
e) Autosomal recessive 4p16 - corneal oedema, deteriorating IQ after age 2, joint stiffness and coarse features
f) Xq26-27. X-linked recessive - affects enzyme HGPRT. Presents with poor muscle control, self-mutilating behaviours, gout (hyperuricaemia and hyperuricosuria). Can present at any time
What prevalence do polymorphisms need to occur in a population?
At least 1%
They must occur with normal but varied presentation (i.e. not disease causing)
Outline different types of polymorphism?
Single nucleotide polymorphisms
Variable tandem repeat polymorphisms:
- Short tandem repeat polymorphism - microsatellites (2-6 bases)
- Minisatellites 20-70 bases
Restriction fragment length polymorphisms - these variations change the site that restriction enzymes act on DNA
Length polymorphisms
What is the founder effect?
Loss of genetic variation that occurs when a new population is established from few members
- acts to maintain polymorphisms - alongside genetic drift and natural selection
How do Southern, Western and Northern blotting vary?
Southern - detection of specific DNA sequence after electrophoresis
Western - detection of specific protein after electrophoresis
Northern - detection of specific RNA after electrophoresis
How many steps does PCR have
3
- DNA is denatured into single strand - then cooled to anneal and primers bind
- DNA polymerase binds to extend length
- Cycling repeats to get necessary amounts
What bacteria does DNA cloning use?
Plasmids
Define heritability
The proportion of variation in a trait (polygenic & quantitative) that is explained by genetic factors
Narrow-sense heritability refers to the variation that is explained by additive gene effects
Broad-sense heritability refers to the variation in phenotype that is explained by (additive + non-additive gene effects).
Non-additive gene effects = epistasis (gene - gene interactions) or dominance (presence of one gene mitigates the effect of another).
What genes affect inheritance of Alzheimer’s?
APOE located on chromosome 19 - affects the breakdown of bAmyloid plaques:
- APOE1 protective
- APOE3 neutral
- APOE4 increased risk (15-30 x if homozygous vs. 3 x if heterozygous)
APP gene - codes for production of APP. Located on chromosome 21 - may account for Alzheimer’s in down’s syndrome
PENS1 - Presenelin 1 - chromosome 14
PENS2 -Presenelin 2 - chromosome 1. These genes code for enzymes that cleave APP - when cleaved abnormally insoluble and becomes Alzheimer’s.
Early onset Alzheimers - most genetic influence PENS1 (30-70%), then APP (10-15%) then PENS2 (5%)
How does most aneuploidy come from?
Non-disjunction of during meiosis 1
- most aneuploidy in humans is from trisomy’s
Name some candidate genes for Schizophrenia
DTNBP1 (dysbindin) - chromosome 6 (6p 22.3): decreased in Schz relates to lower glutamate levels (lyosome related organelles)
COMT - chromosome 22: involved in the breakdown of Dopamine. Low activity levels linked to Schz and OCD
NRG1(neuregulin 1) - chromosome 8 (8p 21-22): growth factor involved in neuron differentiation. High NRG1 level may suppress NMDA receptor and lower glutamate signalling.
G72 - chromosome 13
RGS4 - chromosome 1
DAOA - chromosome 13
DISC1 - chromosome 1: multifactorial protein involved in neuron development
DRD2 - chromosome 11
Name some genes linked with dyslexia
DCD2
GCFC2
ROBO1
MRPL19
DXY1C1
KIAA0319
What is the exam heritability estimates for Sch and BD
50-60%
What mode of inheritance is CADASIL?
Autosomal dominant - associated gene is Notch3
Where do CAG repeats happen on Huntington’s?
Chromosome 4
What is the prevalence of caucasian individuals homozygous for ADH1B*1?
85-95%
ADH1B1 codes for slow metabolism of alcohol to acetaldehyde (unpleasant intermediate that codes for dizziness, nausea and tachycardia)
There are two other loci at similar positions to ADH1B on 4q2123 - ADH1A and ADH1B.
ADH1C1 and ADH1B*2 alleles code for fast metabolism of alcohol
ADH4 has been associated with early onset of drinking
DRD2 (A1 allele) has also been associated with risk factor for alcohol dependence
Apart from ADH1B what other genes have been linked to alcohol use disorder?
ALDH2 - these genes code for aldehyde dehydrogenase that converts acetaldehyde to acetate
ALDH2*504K codes for Asian flush due to fast metabolism of alcohol (tachycardia, facial flushing, nausea) and this is protective for alcohol dependence
Other alleles ALDH21 and ALDH22 are present in 50% of Asian populations and absent outside of Asia
What is the risk of Schz in MZ and DZ twins?
MZ - 50-60%
DZ - 28%
Risk increases if hebephrenic schizophrenia (disorganised)
In Schz symptom severity may not associate greatly to familial risk however age of onset may do
Outline the heritability estimates for BD and the risk in the general population, 1st degree relative and MZ twin
Heritability 85-90%
General population 0.5-1.5%
First degree relative (RR 8) 10-15%
MZ twin (40-70%)
Risk of unipolar depression if have a relative with BD
- First degree relative 10-20%
- MZ twin 15-25%
general population (5-10%)
Name some genes associated with bipolar disorder?
BDNF 11p13
DAO G72/G30 13q33
COMT 22q11 - low activity may associate to rapid cycling
Outline risk of depression in individuals with a first degree relative, MZ twin, DZ twin
1st degree 5-30%
MZ - 40%
DZ 11%
Heritability is 20-80%
Name some genes associated with FTLD
All of below are autosomal dominant:
MAPT (microtubule) associated protein tau gene) 17q21
Or Progranulin 17q21 –> particularly tau negative changes. Progranulin inolved in wound repai, infammation and tumorigenesis
C9orf72 - chromosome 9 (accounts for 20-50% of genetic cases)
Name some of the Parkinson associated genes?
PARK1, PARK4 - dominant - onset in 40a with lewy bodies - gene of alpha synuclein 4q21
PARK 2 - recessive - most common early onset (40-60s), Nigral degeneration without Lewy bodies. Parkin affecting, 6q25. L-DOPA responsive
PARK 8 - dominant - 12 cen pericentromeric LRRK2 gene. Onset in 60s some alpha synuclein and tau
PARK 6 - recessive - earliest onset 30-40s, L-DOPA responsive. 1p35-37 PTEN-INduced Kinase (PINK1) in mitochondria
PARK 7 - recessive - autosomal recessive 30-40s onset 1p38 DJ-1
What is the heritability of Autism?
90%
1st sibling risk 2-8% (50x RR)
If 2 siblings with autism (300x RR)
MZ risk is 60-92%
DZ risk is 0
What is the heritability of Autism?
90%
1st sibling risk 2-8% (50x RR)
If 2 siblings with autism (300x RR)
MZ risk is 60-92%
DZ risk is 0-30%
Chromosomes 2, 7 and 15 have been implicated
Where is the Huntington’s gene (HTT) found
On chromosome 4 - autosomal dominant
Name a gene associated with DLB?
SNCA - located on chromosome 4
GBA (on chromosome 1) or APoE (on chromosome 19) are associated with increased risk
What is Wolf-Hirschorrn syndrome
Syndrome where children get a “greek warrior helmet appearance” to their head with broad flat nose and high forehead. At risk of recurrent seizures as a child
- associated with deletion at short arm (p) of chromosome 4
What does knights move inheritance pattern refer to?
X-linked recessive
What is the inheritance of Kleinfelter’s?
Sporadic
In X-linked dominant how does inheritance follow?
No male to male transmission
All daughters from affected males are cases
What is the risk of developing late stage Alzheimer’s if homozygous for APOE4?
10-30%
What stage of the cell cycle does DNA replication take place?
Synthesis stage
Where is the mutation seen on Smith Magnesis syndrome?
17p
Where does the deletion happen on Cru Di Chat
Terminal end of chromosome 5
What type of mutation is most commonly seen in Beta Thalassaemia
Non-sense mutation in beta-globulin gene that results in reduced/absent HBB gene expression
As autosomal recessive - homozygotes present with severe haemolytic anaemia due to absent HbA production.
Beta-thalassaemia minor the trait condition
Does Tuner’s syndrome present with intellectual diasbility?
Rarely - often IQ comparable to generaly population, sometimes there is visuospatial learning deficits
Results from monosomy of X (45 XO) in females
What is DiGeorge syndrome also known as and how does it present?
Velo-cardiofacial syndrome
- Fish (mouth)
- Pharyngeal insufficiency
- Severe LD
- Supra-valvular aortic stenosis
- Hypocalcaemia
- Hypospadias
- Long thin hands
- Microcephaly
- Cleft palate
- Small mouth
- Long face
- Prominent tubular nose
How do MZ and DZ twins arise?
MZ twins occur when the embryo is cleaved in early childhood:
- Here two genetically identical embryos are made
- 70% of these share the same chorion and therefore have a more similar uterine environment than females
DZ twins are the result of two sperm fertilising one ovum:
- Share 50% of their genes
- Always have their own chorion
If there is a strong family history what is the risk of the child developing alcohol dependence?
4-6 x more likely
The locus of the COMT gene is?
22q11
- note site of DiGeorge microdeletion ?explains the increased risk of Schz 22q11.2
Outline the broad criteria for polymorphisms
Occur in a rate of 1% or above in general population
They are maintained by evolutionary processes
Do not result in functional deficits - they associate with a normal phenotype
What is Kisspeptin 1 and what condition has it been linked to?
Kisspeptin 1 - KISS1 has been linked to Kallman’s syndrome (delayed or absent pubertal onset and loss of sense of smell)
For Huntington’s disease which parent does the gene need to be inherited through to exhibit more a unstable presentation?
Through the father - male germline tends to exhibit earlier presentation
Neuropathy results from intranuclear inclusions of the HTT protein
What is alternative splicing?
Splicing together of exons in different combinations thus to make different proteins out of one gene
Which condition has a deficiency of phenylalanine hydroxylase?
Phenylktonuria (PKU) - autosomal recessive and leads to build up of phenylalanine in the body which can cause severe mental disability.
It can’t be cured but can be managed through reducing levels of phenylalanine in the diet
What does aminoacyl synthetase do?
Aminoacyl synthetase adds the correct amino acid to the tRNA - this is called aminoacylation
Name some symptoms of Rett’s syndrome?
Intellectual disability
Stereotypical hand movements around the midline
Grimacing
Teeth grinding
Ataxia
Loss of speech
It is x-linked recessive and predominantly affects girls
What is a nucleoside?
A nitrogenous base (DNA base) and a pentose sugar - when this is phosphorylated it becomes a nucleotide
DNA is made up of nucleotides with a deoxyribose sugar backbone
When is the Hardy-Weinberg Equation used?
Only to work out the frequency of heterozygotes for carriers of a autosomal recessive condition
p2 + 2pq + q2 = 1
p2 is the frequency of autosomal dominant homozygotes (USUALLY 1)
2pq is the frequency of heterozygotes
q2 is the frequency of autosomal recessive homozygotes
Therefore to the risk of heterozygotes is twice that of frequency of autosomal recessive homozygotes - 2 x (1) x q
In Turners syndrome (45X0) where does the x-chromosome usually come from?
The mother in 80%
This is as paternal error of meiosis often causes the x-not to be transmitted
What genes have been linked with autism?
SHANK1, SHANK2, SHANK3 - codes for SH3 and multiple ankyrin repeat proteins involved in scaffolding present at Glutamatergic synapses in the CNS
What can detect the presence of trinucleotide repeats?
PCR
How to proteasomes know what endogenous cellular components to degrade?
They are labelled with Ubiquitin
How to proteasomes know what endogenous cellular components to degrade?
They are labelled with Ubiquitin
What mode of inheritance is CF?
Autosomal recessive
What is the heritability of ADHD
74% - similar between males and females
More due to genetic > environmental factors
2/3 have ADHD symptoms into adulthood
Candidate genes include: DAT1, DRD4, DRD5, 5HTT, HTR1B, and SNAP25.
How does Williams syndrome present?
Elfin like features, social disinhibition, sensitive hearing, advanced verbal skills but superficial speech (cocktail party speech), can also get hypercalcaemia and endocrine problems
7q11 deletion - most are sporadic
Can be autosomal dominant if inherited
If there is profound LD, seizures, sleep problems, ataxia, flexed arms when walking (flapping hand movements) what condition may you suspect?
Angelman syndrome
Caused from maternal origin 15q11
What is a haplotype?
A set of genetic variations that gets inherited together
A karyotype is an individuals complete set of chromosomes
A genotype is an individuals complete set of genes
Name some x-linked recessive inherited conditions?
Cerebellar ataxia
Hunter’s syndrome
Lesh-Nyan syndrome
As a phenotype is the observable traits what does it reflect?
The interaction between genetic and environmental factors
As a phenotype is the observable traits what does it reflect?
The interaction between genetic and environmental factors
What are the broad names for alcohol associated enzymes?
Alcohol dehydrogenase
Aledhyde dehydrogenase
What is the HTT gene also referred to as?
IT15 on chromosome 4
What are the DNA stop codons?
TAA, TAG TGA
All of these conditions (Phenylketonuria, homocystinuria, Hurler’s syndrome, galactosaemia, Tay-Sach’s disease, Friedrich’s ataxia, Wilson’s disease, cystic fibrosis ) have what mode of inheritance?
Autosomal recessive
How is tuberous sclerosis?
Most are sporadic mutations (3/4) otherwise it is inherited in an autosomal dominant fashion
What is small interfering RNA?
Double stranded RNA molecule that can disrupt the expression of a gene
